Polyimide based substrate comprising doped polyaniline

ABSTRACT

The present invention relates to electrically conductive polyimide films having dispersed in them electrically conductive polymer particles having an average particle size from 0.5 to 5.0 microns. These films are suitable as image transfer belts in high-speed color copying machines and possess a surface smoothness, Ra factor (microns), between 0.5 and 1.5 and a gloss factor between 70 and 120.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to polymeric compositions havingat least one polyimide domain and at least one doped polyaniline domain.More specifically, the compositions of the present invention can becreated by incorporating a stable, doped polyaniline dispersion into apolyamic acid (a polyimide precursor material). The mixture is processedto form a blended polymer substrate (polyimide+doped polyaniline)without having undue gelling or agglomeration of the doped polyanilineparticles.

2. Discussion of the Related Art

Polyimide compositions containing electrically conductive dopedpolyaniline filler particles are known. U.S. Pat. No. 5,567,355, toWessling et. al., teaches a method of forming a doped polyanilinedispersion having an average particle size of less than 500 nanometers.However, such compositions tend to have low gloss factor and/or a roughsurface when used in polyimide blends.

G. Min disclosed procedures for the preparation of polyimide-polyanilineblends in Synth. Met. Vol. 102 (1999), p. 1163-1166, A Solution BlendingMethod. A solution of un-doped polyaniline (also called “Emeraldinebase” or “EB”) is prepared in a polar organic solvent (e.g.dimethylacetamide) in which the polyamic acid (polyimide precursor) isalso soluble. Then, the two solutions are mixed and the resultingmixture cast and dried. The resulting polyimide-EB blend is subsequentlydoped using hydrochloric acid or other protonic acid dopants. However,gelation can be problematic for this type of process, particularly whenmanufacturing and storing the polyaniline (EB) solutions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 discloses the relationship between average particle size vs. Milltime (hrs).

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to stable (or substantially stable),polyaniline dispersions (or suspensions) in a polar organic (orsimilar-type) solvent. Preferably, at least a majority of thepolyaniline domains are doped with a doping agent or similar typecomposition.

The term “polyaniline” is intended to mean an oligomeric or polymericcomposition made from aniline by (usually oxidative) polymerization oralternatively, any other derivative of aniline comprising alkyl, alkoxy,and derivatives thereof.

Polyaniline generally occurs in several forms or compositions, but onlyabout one is conductive. The conductive form is often called “Emeraldinesalt” and is a protonated (“doped”) form of the un-doped, non-conductiveso-called “Emeraldine base” polyaniline. In addition, polyaniline can bereduced (and then later re-oxidized) whereby the fully reduced form iscalled “leucoEmeraldine” polyaniline. The partially oxidized form ofpolyaniline is called “nigraniline”, and the fully oxidized form ofpolyaniline “pernigraniline”. For purpose of doping the polyaniline,protonic and Lewis acids are suitable and will be described later.

In one embodiment of the present invention, a polyimide-based film isprovided, having doped polyaniline particles uniformly dispersedtherein.

In such an embodiment, the average particle size (of the dopedpolyaniline particle in the polyimide base matrix) is preferably fromabout 0.5 microns to (up to) about 5 microns.

In another embodiment, the polyimide based films of the presentinvention can comprise doped, electrically conductive polyanilineparticles having an average particle size between and including any twoof the following: 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, and up to(but not including) 5 microns. During polyamic acid processing (asolution to ultimately obtain a polyimide base matrix) a substantiallystable doped polyaniline dispersion can be injected and mixed into thepolyamic acid.

Generally, the polyaniline particles are thus uniformly dispersed (orsubstantially uniformly dispersed) in the polyimide base matrix.

In one embodiment, films of the present invention have a gloss factorbetween and including any two of the following: 70, 75, 80, 85, 90, 95,100, 105, 110, 115 and 120 and often have a relatively smooth surfacewhere the roughness Ra (microns) number is between and including any twoof the following: 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13,0.14 and 0.15.

In one embodiment, the films of the present invention are (largely orcompletely) devoid of surface imperfections by not having a significantnumber of small gel particles in the film. Thus, these films are oftensuitable in imaging-type applications such as an image transfersubstrate in a high-speed photocopying machine.

In another embodiment of the present invention, the process forpreparing the electrically conductive polyimide blend film includes oneor more of the following:

-   -   (1) polyaniline (in Emeraldine base form) particles dispersed in        a polar solvent,    -   (2) polyaniline particles doped with a doping agent (optionally        in water or another solvent), which will cause the formation of        bigger particles,    -   (3) doped polyaniline particles ground from an average particle        size of about 20 to 200 microns to an average particle size of        from 0.5 microns to 5 microns,    -   (4) doped polyaniline particles dispersed in a selected        dispersion medium are injected into a flowable polyimide        precursor material (i.e. a polyamic acid) and mixed,    -   (5) intermixed, doped polyaniline particles and polyamic acid        being cast and heated into a semi-cured polyamic acid sheet,        and/or    -   (6) interspersed (doped polyaniline) particles in a polyimide        (or polyimide precursor) sheet, cured to form an electrically        conductive polyimide substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Generally, the electrically conductive blend films of the presentinvention comprise two different polymer types. The first polymer is anon-electrically conductive base polymer, typically a polyimide derivedfrom a polyamic acid. The second polymer is a doped polyaniline orsimilar type electrically conductive polymer. The composition of thepresent invention can optionally include other electrically conductivefillers like carbon or metal particles.

The embodiments of the present invention can be designed to provide anyone of a number of useful properties typical of a polyimide, while alsobeing electrically conductive. Advantageous properties associated withthe films of the present invention can include:

-   -   (1) an electrical resistivity between (and including) any two of        the following, 10,000, 10⁵, 10⁶, 10⁷, 10⁸, 10⁹, 10¹⁰, 10¹¹,        10¹², 10¹³, and 10¹⁴ ohms per square,    -   (2) a gloss factor (at an 85 degree angle) between (and        including) any two of the following, 70, 75, 80, 85, 90, 95,        100, 105, 110, 115, and 120,    -   (3) a surface roughness between (and including) any two of the        following, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13,        0.14 and 0.15, and    -   (4) a thickness between (and including) any two of the        following, 5, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65,        70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, and 125        microns.

The present invention is directed to films made by dispersingelectrically conductive polymers (i.e. doped polyaniline) into apolyimide precursor (e.g. a polyamic acid) to form an electricallyconductive film.

In one embodiment, films of the present invention can often be exposedto voltages between and including 50, 100, 500, 1000, 1500, 2000, 2500,3000, 3500, 4000, 4500, and 5000 volts for extended time intervals, e.g.a time period of at least 0.01, 0.1, 0.5, 1, 2, 5, 10, 20 or 30 minutes,without undue change in surface resistivity (and volume resistivity). Incomparison, many conventional conductive films tend to drift in anegative direction (i.e. the film will become more electricalconductivity over time) as voltage is applied.

The conductive polyimide/polyaniline films of the present invention willgenerally have one or more of the following properties:

-   -   (I) a relatively constant resistivity over different voltages,        exposure times, operating temperatures (from 0 to 45° C.), and        operating humidity fluctuations (typically, ranging from 10 to        85 percent),    -   (II) a smooth film surface where the gloss factor is between 70        and 120, and    -   (III) a smooth film surface where the surface roughness, Ra        factor (microns), is between 0.05 and 0.15.

Doped (or un-doped) polyaniline dispersions in solvents commonly used tomake polyimides, can tend to gel (either partially or totally) if theaverage particle size of the polyaniline particle is too small. If theaverage particle size of the polyaniline particles is too large, thedispersion can flocculate and larger particles can settle.

Applicant has surprisingly discovered that there exists a range ofparticle sizes where polyaniline slurries can generally be made to bestable (relatively low levels of unwanted gelling, if any). This is truewhen the polyaniline particles are doped with an acid, and oftentimes toa somewhat lesser degree, if the polyaniline particles are un-doped. Inthe case of polyaniline particles dispersed in dimethylacetamide solvent(a solvent commonly used to make polyimides), the particles mustgenerally have an average particle size in a range between any two ofthe following numbers: 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0 andup to but not including 5 microns.

If the average particle size of the polyaniline particles is less than0.5 microns, the surface energy (and surface area) of the dopedelectrically conductive polyaniline particles can often be incompatiblewith the other slurry components resulting in unwanted gelling of theslurry. These (less than 0.5 micron) slurries, under normal agitation(and in some cases under a moderate amount of shearing force) aregenerally not stable and will often gel over time, especially if made insolvents commonly used to manufacture polyimides. The polyimide blendfilms made from these polyaniline dispersions can have a high number ofsurface defects, undesirable high surface roughness, and low surfacegloss factor (i.e. have a matte finish).

Regarding embodiments of the present invention involving polyanilineparticles dispersed in dimethylacetamide (a typical solvent used in themanufacture of polyimides) when the average particle sizes is below 0.5microns, the particles may have too high a surface area and/or surfaceenergy to form a stable dispersion. This can be especially evident whenthe polyaniline dispersion is at a concentration greater than 1.0, 2.0,3.0, 4.0, 5.0, 6.0, or 7.0 weight percent in dimethylacetamide solvent.

“Gelling” as used herein is intended to mean that the average particlesize of the doped polyaniline particles increases to greater than 5, 8,10, 12, 15, 17, 18, 19 or 20 microns. The present invention is generallyfree of unwanted gelling that often results in the size of the averagepolyaniline particle becoming so large that filtering the dispersion (orthe mixed polymer blend) is impractical or impossible.

If the average particle size of the doped polyaniline particle isgreater than 5 microns, often the larger particles will tend toagglomerate (i.e. aggregate with other large and small particles) toform even larger agglomerates that precipitate. Agglomeration rates havebeen observed to be somewhat slower than gelling rates, but the resultin the blend films formed therefrom is generally the same. Films madefrom these slurries will oftentimes have high surface roughness and alarge number of surface defects (commonly seen as ‘bumps’ on the surfaceof the film).

In other cases, when polyaniline powder properties are less than optimal(e.g. very high molecular weight or a high degree of impurities presentin the polyaniline) preparing a stable polyaniline dispersion, havingfrom one to 5 weight percent solids, can be problematic. The presentinvention surprisingly shows that a wider range of commerciallyavailable polyaniline powders (i.e. powders that contain impurities) arenow viable as starting materials to make polyimide/polyaniline blendfilms. It has been discovered that by controlling the average particlesize distribution of the polyaniline slurry, an advantageous method ofmaking a stable slurry, irrespective of the molecular weight of thepolyaniline or the impurity content, has been discovered.

The preparation of such dispersions with a medium range of particle size(in a range of about 0.5 μm to about 5.0 μm) requires a controlledprocedure. Two preferred approaches (including derivations andmodifications thereof) can be used within the scope of this invention:

-   -   a) The solution or ultra-fine dispersion of an un-doped form of        polyaniline (the Emeraldine base) is prepared in a suitable        solvent, optionally followed by the addition of a weak        dispersion medium. This causes the formation of bigger particles        that are then ground to the particle size range as needed.        Doping of the Emeraldine base dispersion could be performed        either in parallel to the addition of the non-solvent/weak        dispersion medium or could be performed after this step. In        addition, doping could be done prior to or after the grinding        step. Doping may also be done with the mixing of the polyaniline        dispersion with the polyamic precursor solution. It is often        preferred to use solvents that are miscible with the polyamic        acid.    -   b) The Emeraldine base slurry (suspension) in any solvent can be        doped, and, if necessary dried to a moisture level, or solvent        level, that is appropriate to make a polyimide. Then, the        pre-doped polyaniline dispersion, in the selected solvent medium        can be mixed with a solvent appropriate to make a polyimide        (e.g. dimethylacetamide) and then mixed with a polyimide        precursor (e.g. a polyamic acid solution).

In one embodiment of the present invention, a stable polyaniline slurryis formed by first dispersing un-doped polyaniline (Emeraldine base)particles in a polar solvent under high shear. After the initialparticles are dispersed, a dopant (dissolved in water) is added wherebythe non-solvent/weak dispersion medium (respectively) is introduced. Theslurry is then milled through a particle-size reduction media so thatthe final average particle size of the polyaniline particles is reducedto from about 20 to 200 microns to a range of about 0.5 microns to (upto) 5.0 microns.

When the average particle size of the doped polyaniline particles in theliquid dispersion is from 0.5 microns to (up to) 5 microns, the slurryis generally stable over time (particularly under moderate agitation ina feed tank or otherwise). Generally under such conditions, the averageparticle size (of the dispersion) does not change significantly (i.e.increase to an average particle size of 5.0 microns or more) at leastfor a period of time (typically at least seven days or more).

The polyimide/polyaniline blend film formed from these dispersionsgenerally has a smooth surface only and few defects (which are tolerableso long as they are within acceptable technical specifications) comparedto a film made from slurries where the average particle size is outsidethe range of from 0.5 microns to 5.0 microns (or any sub-range thereto).The films made according to the following invention are ideal for use asan image transfer belt or a substrate in a flexible circuit package.

In one embodiment of the present invention, blend films can be obtainedby dispersing pre-doped or un-doped polyaniline particles indimethylacetamide (DMAc). When using an un-doped polyaniline, generallythe particles can be doped by adding a doping agent to the liquiddispersion. Doping may also be performed in situ by adding the dopingagent after the polyaniline particles are mixed with the polyamic acid(or at the same time, the polyaniline particles are mixed with thepolyamic acid). Generally, the doping of the polyaniline may beperformed before (or after) the polyaniline particle size reduction.

For films of the present invention, doping of the polyaniline particlesmay be performed at less than 100 percent doping. Doping generallyrequires that an acid group associate with the conjugated moiety of thepolyaniline molecular chain. By chemical association of the acid to thepolyaniline chain, the polyaniline chain is made to be electricallyconductive. However, not every conjugated moiety of the polyanilinechain must have an acid associated group. In some cases, the polyanilinechain may be doped with 1, 3, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90or 99 percent dopant. If less than 100 percent dopant is used, typicallymore polyaniline concentration in the polyimide blend film is requiredto reach a target resistivity.

The films of the present invention can be produced by first doping apolyaniline powder in the presence of an organic solvent to form anelectrically conductive, polyaniline particle dispersion. The initialliquid dispersions formed are typically too large to be injecteddirectly into a polyamic acid. These slurries typically have an averageparticle size between 20 and 200 microns and are generally unstable overtime (i.e. will gel or agglomerate).

Oftentimes it is important to reduce the average particle size of thepolyaniline particles after the initial dispersion has been prepared. Asused herein the term “target particle size distribution” is intended tomean a polyaniline liquid dispersion having an average particle sizefrom 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, and (up to) 5 microns.When using a pre-doped polyaniline powder, the doping step is typicallyeliminated. However, compositions of the present invention, can bederived from polyaniline dispersions using (i) pre-doped polyaniline(ii) un-doped polyaniline (and then doping it in situ), or (iii)un-doped polyaniline and never doping it. The dispersion can be groundto the target particle size distribution (in an environment of shearingforce) so that the dispersion reaches an average particle size rangefrom 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, and 5 microns.

A protic acid can be used as the dopant for the polyaniline,particularly useful protic acids are acids with an acid dissociationconstants (pKa) of 4.8 or lower. Examples of such acids include sulfuricacid, nitric acid, phosphoric acid, hypophosphoric or phosphonic acids,hydrofluoroboric acid, hydrofluorophosphoric acid, and hydrochloricacid. Other useful acids (as dopants) include aliphatic acids, aromaticacids, alicyclic acids, and polybasic acids. These organic acids canalso have hydroxyl groups, halogens, nitrile groups, cyano groups, andamino groups. Other less common, but useful acids include acetic acid,n-butyric acid, pentadecafluorooctanoic acid, pentafluoro-acetic acid,trifluoroacetic acid, trichloroacetic acid, dichloroacetic acid,monofluoroacetic acid, monobromoacetic acid, monochloroacetic acid,cyanoacetic acid, acetyl acetic acid, nitroacetic acid, triphenyl aceticacid, formic acid, oxalic acid, benzoic acid, m-bromo-benzoic acid,p-chlorobenzoic acid, m-chlorobenzoic acid, p-chlorobenzoic acid,o-nitrobenzoic acid, 2,4-dinitrobenzoic acid, 3,5-dinitrobenzoic acid,picric acid, o-chlorobenzoic acid, p-nitrobenzoic acid, m-nitrobenzoicacid, trimethyl benzoic acid, p-cyanobenzoic acid, m-cyanobenzoic acid,thymol blue, salicylic acid, 5-amino salicylic acid, o-methoxy benzoicacid, 1,6-dinitro-4-chlorophenol, 2,6-dinitrophenol, 2,4-dinitrophenol,p-oxybenzoic acid, bromophenol blue, mandelic acid, phthalic acid,isophthalic acid, maleic acid, fumaric acid, malonic acid, tartaricacid, citric acid, lactic acid, succinic acid, glycine, glycolic acid,thioglycolic acid, ethylene diamine-N,N′-diacetic acid, and ethylenediamine N,N,N′,N′-tetracetic acid.

Moreover, useful acids can have sulfonic acid or sulfuric acid groups.Examples of such acids are amino naphthol sulfonic acid, metanilic acid,sulfanilic acid, allyl sulfonic acid, lauryl sulfuric acid, xylenesulfonic acid, chlorobenzene sulfonic acid, methane sulfonic acid,ethane sulfonic acid, 1-propane sulfonic acid, 1-butane sulfonic acid,1-hexane sulfonic acid, 1-heptane sulfonic acid, 1-octane sulfonic acid,1-nonane sulfonic acid, 1-decane sulfonic acid, 1-dodecane sulfonicacid, benzenesulfonic acid, styrene sulfonic acid, p-toluene sulfonicacid, naphthalene sulfonic acid, ethyl benzenesulfonic acid, propylbenzenesulfonic acid, butyl benzenesulfonic acid, pentyl benzenesulfonicacid, hexyl benzenesulfonic acid, heptyl benzenesulfonic acid, octylbenzenesulfonic acid, nonyl benzenesulfonic acid, decyl benzenesulfonicacid, undecyl benzenesulfonic acid, dodecyl benzenesulfonic acid,pentadecyl sulfonic acid, octadecyl benzenesulfonic acid, diethylbenzenesulfonic acid, dipropyl benzenesulfonic acid, dibutylbenzenesulfonic acid, methyl naphthalene sulonic acid, ethyl naphthalenesulfonic acid, propyl naphthalene sulfonic acid, butyl naphthalenesulfonic acid, phentyl naphthalene sulfonic acid, hexyl naphthalenesulfonic acid, heptyl naphthalene sulfonic acid, octyl naphthalenesulfonic acid, nonyl naphthalene sulfonic acid, pentadecyl naphthalenesulfonic acid, octydecyl naphthalene sulfonic acid, dimethyl naphthalenesulfonic acid, diethyl naphthalene sulfonic acid, dipropyl naphthalenesulfonic acid, dibutyl naphthalene sulfonic acid, dipentyl naphthalenesulfonic acid, dihexyl naphthalene sulfonic acid, diheptyl naphthalenesulfonic acid, dioctyl naphthalene sulfonic acid, dinonyl naphthalenesulfonic acid, timethyl naphthalene sulfonic acid, triethyl naphthalenesulfonic acid, tripropyl napohthalene sulfonic acid, tributylnaphthalene sulfonic acid, camphor sulfonic acid, and acrylamide-t-butylsulfonic acid.

In the case of dispersing leucoEmeraldine based polyaniline (achemically reduced polyaniline having protons donated to it by a strongreducing agent), the leucoEmeraldine based polyaniline particlesgenerally can be relatively small. These polyaniline particles have anaverage particle size in the range of 5 to 50 nanometers. In the case ofproducing a polyaniline dispersion in DMAc, the leuco-based polyaniline(in the presence of dopant or not in the presence of a dopant) can gelin a matter of hours.

Phenyl hydrazine, hydrazine, hydrazine hydrate, hydrazine sulfate,hydrazine chloride, and other hydrazine compounds, or reducinghydrogenated metal compounds, such as lithium aluminum hydride, andlithium borohydride, may be used as reducing agents. A residue generallydoes not form after the reduction reaction and therefore hydrazinehydrate or phenyl hydrazine is often preferred as a reducing agent.

In one embodiment of the present invention, useful solvents are used toprocess the polyimide component and the polyaniline component. Thesesolvents include (normally liquid) N,N′-dialkylcarboxylamides and thelower molecular weight members of carboxylamides, particularlyN,N′-dimethylformamide and N,N′-dimethylacetamide. Still other usefulcompounds of this class of solvents include N,N′-diethylformamide andN,N′-diethylacetamide. Other solvents that may be useful includedimethylsulfoxide, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone,tetramethyl urea, gamma-butyrolactone, dimethylsulfone,hexamethylphosphoramide, tetramethylenesulfone, diglyme, pyridine andthe like. The solvents listed above can be used alone, in combinationswith one another solvent, or in combinations with other solvents such astoluene, xylene, benzonitrile, and dioxane.

In another embodiment of the present invention, useful solvents arecharacterized by their surface tension. In this embodiment, the surfacetension of these useful solvents is between any two of the followingnumbers, 34, 35, 36, 37, 38, 39, 40, 41 or 42 mN/m. These solvents maybe used alone or in combination with weak dispersion mediums.

As used herein the term “weak dispersion mediums” describes a liquidthat has a surface tension between (and including) any two of thefollowing numbers, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,33, or 33.5 mN/m or between (and including) any two of the followingnumbers, 42, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 125, 150,200, 300, 400, and 500 mN/m. Weak dispersion mediums include, but arenot limited to, alcohols, ethers, ketones and water. It is important tonote that water (or any other useful solvent or weak dispersion medium)may not be used to such an extent that it would inhibit, or act as achain terminator, of the polyamic acid polymerization reaction.

In one embodiment of the present invention, a weak dispersion medium isused in combination with a useful solvent. A weak dispersion medium isgenerally added to a polyaniline dispersion (e.g. a leucoEmeraldine basepolyaniline) to increase the average particle size of the polyanilineparticles. For example, when the average particle size of thepolyaniline particles is below 500 nanometers a weak dispersion mediumcan be added to increase the particle size of the polyaniline particlesto the target particle size distribution. Generally speaking, weakdispersion mediums are miscible with the useful solvents mentionedabove.

In accordance with the present invention, polyaniline liquid dispersionshaving an average particle size larger than 5.0 microns are ground to asmaller average particle size. This is done using any known(conventional or non-conventional) means of particle size reductionincluding kinetic dispersion (using a rotor/stator assembly at highrevolution), ultra-sonic wave methods, media milling (in either acontinuous media mill or batch media mill), or the like.

The most common means of particle size reduction is by mechanicalgrinding (or the mechanical manipulation of) the subject particles usingfine media stirred under low shear over long periods. When using a finemedia to reduce the average particle size of the particles in theslurry, the slurry can be pumped from a high shear environment through ahorizontal media mill. The media in the mill (beads of zirconium,yttrium, or the like) can be agitated by turning rotors. The movingmedia (media rubbing against other media) generally causes the shearingforce to grind the particles of the slurry as the slurry is pumpedthrough the mill. Once the target particle size distribution of theslurry is reached, the slurry will then generally be stable enough(especially at concentrations from one to 15 weight percent) to bestored under slow agitation.

In one embodiment of the present invention, the milling (or grinding) ofthe doped polyaniline particle dispersion is performed in a horizontalmedia mill. The average particle size of the doped polyaniline particleis reduced from 20 to 200 microns to about 0.5 microns to 5 microns inabout twenty-four to seventy-two hours. When the average particle sizeof the dispersion reaches the range of from 0.5 to 5.0 microns, thedoped polyaniline dispersion is stable over time in the polar solvents.

In another embodiment, the doped polyaniline dispersions typically havea solids weight percent in a solvent ranging between 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, and30 weight percent.

The term “stable doped polyaniline particle dispersion” is intended tomean a polyaniline particle dispersion where the average particle sizeis from 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, and 5 microns andwhere the dispersion will not change its average particle size by morethan 10, 20, 40, 60, 80, 100, 150, 200, 300, 400, 500 or 1000 percent ofits original value over a 4, 6, 8, 12, 16, 20, 24, 48, 72, 96, or 120hour period.

In one embodiment, the doped polyaniline particle dispersions mentionedabove are next injected into a polyimide precursor (commonly a polyamicacid). The two components are mixed under high shear to form a mixedpolymer blend. The mixed polymer blend may be further filtered ordegassed to remove larger unwanted particles or unwanted gasses. Thepolyamic acid can be an aromatic polyamic acid prepared bycopolymerizing substantially equimolar amounts of an aromatictetracarboxylic dianhydride (or the dianhydride's acid, acid ester, oracid halide ester derivative) with an aromatic diamine component. In oneexample, the dianhydride component is 3,3′,4,4′-biphenyltetracarboxylicdianhydride (i.e. 3,3′,4,4′-BPDA) optionally blended with pyromelliticdianhydride (PMDA). In this same embodiment, the diamine component isp-phenylenediamine (PPD) optionally blended with a diaminodiphenyl etherlike 3,4′-oxydianiline (3,4′-ODA) or 4,4′-oxydianiline (4,4′-ODA). Thedianhydrides first may be blended together or added individually toeither one, or blended with all of the diamines to form a polyamic acidpolymer that is either a block (segmented) copolymer or a randomcopolymer.

Examples of suitable tetracarboxylic dianhydrides (and functionalderivatives thereof) that are useful in accordance with this embodimentof the present invention include:

-   -   1. pyromellitic dianhydride (PMDA);    -   2. 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA);    -   3. 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA);    -   4. 4,4′-oxydiphthalic anhydride (ODPA);    -   5. bis(3,4-dicarboxyphenyl) sulfone dianhydride (DSDA);    -   6. 2,2-bis(3,4-dicarboxyphenyl) 1,1,1,3,3,3,-hexafluoropropane        dianhydride (6FDA);    -   7. 2,2′-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride        (BPADA);    -   8. 2,3,6,7-naphthalene tetracarboxylic dianhydride;    -   9. 1,2,5,6-naphthalene tetracarboxylic dianhydride;    -   10. 1,4,5,8-naphthalene tetracarboxylic dianhydride;    -   11. 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride;    -   12. 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride;    -   13. 2,3,3′,4′-biphenyl tetracarboxylic dianhydride;    -   14. 2,2′,3,3′-biphenyl tetracarboxylic dianhydride;    -   15. 2,3,3′,4′-benzophenone tetracarboxylic dianhydride;    -   16. 2,2′,3,3′-benzophenone tetracarboxylic dianhydride;    -   17. 2,2-bis(3,4-dicarboxyphenyl) propane dianhydride;    -   18. 1,1-bis(2,3-dicarboxyphenyl) ethane dianhydride;    -   19. 1,1-bis(3,4-dicarboxyphenyl) ethane dianhydride;    -   20. bis(2,3-dicarboxyphenyl) methane dianhydride;    -   21. bis(3,4-dicarboxyphenyl) methane dianhydride;    -   22. 4,4′-(hexafluoroisopropylidene) diphthalic anhydride    -   23. bis(3,4-dicarboxyphenyl) sulfoxide dianhydride;    -   24. tetrahydrofuran-2,3,4,5-tetracarboxylic dianhydride;    -   25. pyrazine-2,3,5,6-tetracarboxylic dianhydride;    -   26. thiophene-2,3,4,5-tetracarboxylic dianhydride;    -   27. phenanthrene-1,8,9,10-tetracarboxylic dianhydride;    -   28. perylene-3,4,9,10-tetracarboxylic dianhydride;    -   29. bis-1,3-isobenzofurandione;    -   30. bis-(3,4-dicarboxyphenyl) thioether dianhydride;    -   31.        bicyclo-[2,2,2]-octen-(7)-2,3,5,6-tetracarboxylic-2,3,5,6-dianhydride;    -   32. 2-(3′,4′-dicarboxyphenyl) 5,6-dicarboxybenzimidazole        dianhydride;    -   33. 2-(3′,4′-dicarboxyphenyl) 5,6-d icarboxybenzoxazole d ian        hydride;    -   34. 2-(3′,4′-dicarboxyphenyl) 5,6-d icarboxybenzothiazole d ian        hydride;    -   35. bis (3,4-dicarboxyphenyl) 2,5-oxadiazole 1,3,4-dianhydride;    -   36. bis-2,5-(3′,4′-dicarboxydiphenylether) 1,3,4-oxadiazole        dianhyd ride;    -   37. their acid ester and acid halide ester derivatives;    -   38. and the like.

Representative dianhydrides which are particularly preferred in thepresent invention include pyromellitic dianhydride (PMDA),4,4′-oxydiphthalic anhydride (ODPA), bis(3,4-dicarboxyphenyl) sulfonedianhydride, 2,2-bis(3,4-dicarboxyphenyl) 1,1,1,3,3,3,-hexafluoropropanedianhydride (6FDA), 2,2′-bis[4-(3,4-dicarboxyphenoxy)phenyl]propanedianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA),bis(3,4-dicarboxyphenyl) sulfone dianhydride (DSDA),2,2′-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA).

Examples of suitable aromatic diamines (and functional derivativesthereof) useful in accordance with this embodiment of the presentinvention include:

-   -   1 2,2 bis-(4-aminophenyl) propane;    -   2. 4,4′-diaminodiphenyl methane;    -   3. 4,4′-diaminodiphenyl sulfide;    -   4. 3,3′-diaminodiphenyl sulfone;    -   5. 4,4′-diaminodiphenyl sulfone;    -   6. 4,4′-diaminodiphenyl ether (4,4′-ODA);    -   7. 3,4′-diaminodiphenyl ether (3,4′-ODA);    -   8. 1,3-bis-(4-aminophenoxy) benzene (APB-134 or RODA);    -   9. 1,3-bis-(3-aminophenoxy) benzene (APB-133);    -   10. 1,2-bis-(4-aminophenoxy) benzene;    -   11. 1,2-bis-(3-aminophenoxy) benzene;    -   12. 1,4-bis-(4-aminophenoxy) benzene;    -   13. 1,4-bis-(3-aminophenoxy) benzene;    -   14. 1,5-diaminonaphthalene;    -   15. 2,2′-bis(trifluoromethyl)benzidine (TFMB);    -   16. 4,4′-diaminodiphenyldiethylsilane;    -   17. 4,4′-diaminodiphenylsilane;    -   18. 4,4′-diaminodiphenylethylphosphine oxide;    -   19. 4,4′-diaminodiphenyl-N-methyl amine;    -   20. 4,4′-diaminodiphenyl-N-phenyl amine;    -   21. 1,2-diaminobenzene (OPD);    -   22. 1,3-diaminobenzene (MPD);    -   23. 1,4-diaminobenzene (PPD);    -   24. 2,5-dimethyl-1,4-diaminobenzene;    -   25. 2,5-dimethyl-1,4-phenylenediamine (DPX);    -   26. trifluoromethyl-2,4-diaminobenzene;    -   27. trifluoromethyl-3,5-diaminobenzene;    -   28. 2,2-bis(4-aminophenyl) 1,1,1,3,3,3-hexafluoropropane (6F        diamine);    -   29. 2,2-bis(3-aminophenyl) 1,1,1,3,3,3-hexafluoropropane;    -   30. benzidine;    -   31. 4,4′-diaminobenzophenone;    -   32. 3,4′-diaminobenzophenone;    -   33. 3,3′-diaminobenzophenone;    -   34. m-xylylene diamine;    -   35. p-xylylene diamine;    -   36. bisaminophenoxyphenylsulfone;    -   37. 4,4′-isopropylidenedianiline;    -   38. N,N-bis-(4-aminophenyl) methylamine;    -   39. N,N-bis-(4-aminophenyl) aniline    -   40. 3,3′-dimethyl4,4′-diaminobiphenyl;    -   41. 4-aminophenyl-3-aminobenzoate;    -   42. 2,4-diaminotoluene;    -   43. 2,5-diaminotoluene;    -   44. 2,6-diaminotoluene;    -   45. 2,4-diamine-5-chlorotoluene;    -   46. 2,4-diamine-6-chlorotoluene;    -   47. 2,4-bis-(beta-amino-t-butyl) toluene;    -   48. bis-(p-beta-amino-t-butyl phenyl) ether;    -   49. p-bis-2-(2-methyl-4-aminopentyl) benzene;    -   50. 1-(4-aminophenoxy)-3-(3-aminophenoxy) benzene;    -   51. 1-(4-aminophenoxy)-4-(3-aminophenoxy) benzene;    -   52. 2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP);    -   53. bis-(4-(4-aminophenoxy)phenyl sulfone (BAPS);    -   54. 4,4′-bis(3-aminophenoxy)diphenylsulfone (m-BAPS);    -   55. 4,4′-bis-(aminophenoxy)biphenyl (BAPB);    -   56. bis(4-[4-aminophenoxy]phenyl) ether (BAPE);    -   57. 2,2′-bis-(4-phenoxy aniline) isopropylidene;    -   58. 2,4,6-trimethyl-1,3-diaminobenzene;    -   59. 4,4′-diamino-2,2′-trifluoromethyl diphenyloxide;    -   60. 3,3′-diamino-5,5′-trifluoromethyl diphenyloxide;    -   61. 4,4′-trifluoromethyl-2,2′-diaminobiphenyl;    -   62. 4,4′-oxy-bis-[(2-trifluoromethyl) benzene amine];    -   63. 4,4′-oxy-bis-[(3-trifluoromethyl) benzene amine];    -   64. 4,4′-thio-bis-[(2-trifluoromethyl) benzene-amine];    -   65. 4,4′-thiobis-[(3-trifluoromethyl) benzene amine];    -   66. 4,4′-sulfoxyl-bis-[(2-trifluoromethyl) benzene amine];    -   67. 4,4′-sulfoxyl-bis-[(3-trifluoromethyl) benzene amine];    -   68. 4,4′-keto-bis-[(2-trifluoromethyl) benzene amine];    -   69. and the like.

In one embodiment, preferred aromatic diamines include1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 4,4′-diaminodiphenylether (4,4′-ODA), 3,4′-diaminodiphenyl ether (3,4′-ODA),1,3-bis-(4-aminophenoxy) benzene (APB-134), 1,3-bis-(3-aminophenoxy)benzene (APB-133), 2,2-bis-[4-(4-aminophenoxy)phenyl]propane (BAPP),bis-(4-(4-aminophenoxy)phenyl sulfone (BAPS),4,4′-bis(3-aminophenoxy)diphenylsulfone (m-BAPS),4,4′-bis-(aminophenoxy)biphenyl (BAPB), bis(4-[4-aminophenoxy]phenyl)ether (BAPE), 2,2′-bis(trifluoromethyl)benzidine (TFMB), and2,2-bis-(4-aminophenyl) 1,1,1,3,3-hexafluoro propane (6F diamine).

Aliphatic and cycloaliphatic diamines are also useful diamine monomers(typically as co-diamines), useful in making the polyamic acidprecursors (and then the polyimides) of the present invention. Usefulaliphatic diamines are 1,4-tetramethylenediamine,1,5-pentamethylenediamine (PMD), 1,6-hexamethylenediamine (HMD),1,7-heptamethylene diamine, 1,8-octamethylenediamine,1,9-nonamethylenediamine, 1,10-decamethylenediamine (DMD),1,11-undecamethylenediamine, 1,12-dodecamethylenediamine (DDD),1,16-hexadecamethylenediamine. Useful cycloaliphatic diamines arepara-amino cyclohexylmethane (PACM), isophorone diamine (IPD), anddiaminocyclohexane (especially 1,4-diaminocyclohexane).

The diamines of the present invention may be used alone or in mixturesof two or more diamines. The diamines and the tetracarboxylicdianhydrides can be reacted by any conventional or non-conventionalmethod to give a polyamic acid. Methods used to form polyamic acids arewell known in the art and are not discussed herein.

The aromatic polyamic acid of the present invention can be prepared bypolymerizing substantially equimolar amounts of the aforesaid aromatictetracarboxylic acid and aromatic diamine components at an appropriatepolymerization temperature, such as 175° C. or less, more preferablyabout 90° C. or less, and most preferably 50° C. or less. This reactiontakes place for about one minute to several days in an inert organicsolvent depending on the temperature. The aromatic tetracarboxylic acidand aromatic diamine components can be added either neat, as a mixtureor as solutions to the organic solvent or the organic solvent may beadded to the components.

It is not required that the aromatic tetracarboxylic acid and thearomatic diamine components be used in absolute equimolar amounts. Inorder to adjust the molecular weight, the mole ratio of thetetracarboxylic acid component to the diamine component can range from0.90 to 1.10, but is typically 0.98 to 1.02.

In one embodiment, the polyamic acid solution contains from 5 to 40weight percent, preferably 10 to 25 weight percent, of polyamic acidpolymer.

Once the polyamic acid and doped polyaniline particles are appropriatelyinter-dispersed (to form a mixed polymer blend), the polyamic acidlinkages can be subjected to cyclo-dehydration (a ring-closing reaction)to obtain a polyimide using a thermal conversion process. Optionally,chemical agents can be used to enhance the imidization reaction (e.g.dehydrating agents like acetic anhydride and catalysts likebeta-picoline).

In one embodiment of the present invention, the mixed polymer blendmentioned above can then be cast onto a flat surface using a slot die toform a wet film. The wet film can then heated and dried to form asemi-cured sheet. The heating conditions range from generally 50, 70,90, 110, 130, 150, 170, to 190° C. over a period of 10, 20, 30, 40, 50,or 60 minutes.

The semi-cured sheet can then processed through a curing oven where thefilm is stretched and additionally heated so that the polyamic acid isfully converted into a polyimide. The heating conditions range from 250,300, 350, 400, 450, 500, 550, 600 and 650° C. over a period of 5, 10,15, 20, 25, 30, 35 and 40 minutes.

In making the blend films of the present invention (i.e. films derivedfrom a polyaniline component being dispersed in a polyimide component)it may be desirable to select a polyimide component derived from BPDA,PMDA, 4,4′-ODA and PPD monomers (i.e. monomers that when chemicallyreacted together form a polyimide component with a high glass transitiontemperature). On the other hand, it may be desirable to select apolyimide component derived from PMDA, ODPA, and RODA monomers (i.e.monomers that when chemically reacted together form a polyimide having alow glass transition temperature).

As used herein the term non-thermoplastic polyimide is used to describea polyimide component that has a glass transition temperature greaterthan 300° C., preferably greater than 350° C., and most preferablygreater than 400° C. As used herein the term thermoplastic polyimide isused to describe a polyimide component that has a glass transitiontemperature less than or equal to 300° C., preferably less than 250° C.,and most preferably less than 220° C.

Non-thermoplastic polyimides, at certain monomer ratios, can be made toform a polyimide component (or combination with a doped polyanilinecomponent) that has a coefficient of thermal expansion close to that ofmetal (particularly copper). This is ideal in flexible circuitryapplications where low dissipation loss is an important property toachieve.

Thermoplastic polyimides, at certain monomer ratios, can be made to forma polyimide component that has adhesive properties. This is particularlyuseful in applications where the polyimide component, or the combinationof the polyimide component and a doped polyaniline component, needs tobe bonded to another material or itself.

As used herein, the term “self-adherable” polyimide is used to describea film (either a pure polyimide or a blend film containing a polyimidecomponent and a polyaniline component) that if exposed to hightemperature and pressure, the film can adequately bond to itself.Typically, self-adherable films can require a temperature of at least250, 275, 300, 325, 350, 375, and 400° C. and a pressure of at least 1,10, 25, 50, 75, 100, 200, 300, 500, and 1000 (psi). Generally, bondingof self-adherable films occurs between 1, 3, 5, 10, 20, 30, and 60minutes. Self-adherable films are generally useful as image transferbelts in color copying machines.

In one embodiment of the present invention the polyimide/polyanilineblended sheets have uniformly dispersed therein electrically conductive(doped) polyaniline particles so that the final film has a surfaceresistivity between any two of the following numbers, 10,000, 10⁵, 10⁶,10⁷, 10⁸, 10⁹, 10¹⁰, 10¹¹, 10¹², 10¹³, and 10¹⁴ ohms per square.

In another embodiment, the substrate of the present invention has atotal thickness in a range between and including any two of thefollowing: 5, 8, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,80, 85, 90, 95, 100, 105, 110, 115, 120, and 125 microns.

In another embodiment of the present invention, thepolyimide/polyaniline blend films have a gloss factor between any two ofthe following numbers, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, and120.

In yet another embodiment of the present invention, the blend films havea surface roughness, or also known as an Ra factor (microns) between anytwo of the following numbers, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11,0.12, 0.13, 0.14 and 0.15. The film is also smooth enough to be used asan image transfer belt.

In one embodiment, the amount of doped polyaniline used in accordancewith the present invention is in a range of from 5 to 60 weight percent(based upon the total weight of the doped polyaniline and polyimide),and depending upon the desired end use properties, can be used in arange from 10 to 20 percent. If doped polyaniline concentration is below5 weight percent, the composite film may not show improved electricalconductivity compared to a pure polyimide. If the amount of dopedpolyaniline exceeds 60 weight percent (or 120 parts doped polyanilineper 100 parts polyimide), the film may have low dielectric strength, andwill often have low mechanical strength. The weight ratio of dopedpolyaniline to polyimide can represented by the ratio A to B (A:B),where A is the doped polyaniline and B is the polyimide. In accordancewith the present invention, A is a range between and including any twoof the following weight parts: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55and 60, and B is a range between and including any two of the followingweight parts: 95, 90, 85, 80, 75, 70, 65, 60, 55, 50, 45, or 40. In oneembodiment, the amount of doped polyaniline in the final composition isat least 10, 12, 14, 16, 18 or 20 weight percent of the entire finalcomposition.

Ideally, the films of the present invention are produced with thenecessary film drawing ratios during curing so that the volumeresistivity (measured in ohm-cm) is equivalent to, or no more than twoorders of magnitude from, the surface resistivity. If the film is drawnby too high a factor in the x-y plane of the film, the surfaceresistivity will often decrease. If however, the film is not drawnenough in the x-y plane, the polyimide may have too low a modulus.

The blend films of the present invention are substantially devoid oflarge electrically conductive particle, particles greater than 5.0microns, however a small amount, less than 1.0 percent by weight maystill exist.

The films of the present invention are generally well suited for use asan imaging transfer belt in high-speed color copying machines or can beuseful as electronic substrates as well as “electrical resist layers” inflexible, or rigid, circuitry applications. These films are also ideallysuitable as electrode materials for electrode cells, magnetic shields,electrostatic absorption films, anti-static materials, video recorderparts, and other electronic devices.

In another curing method, the polyamic acid/doped polyaniline mixedpolymer blend is cast onto a metal foil. This is commonly called acast-on-metal or cast-on-copper method. Here, the metal layer and thepolymer cast onto the metal layer are heated so that the polyamic acidis cured to a polyimide. The result is a polymer-on-metal product.

The polymer blend film composites of either the stand-alone film, or thecast-on-metal product possess properties inherent to both the dopedpolyaniline (i.e. “electrical conductivity”) and the polyimide resin(i.e. mechanical strength properties and chemical/thermal resistance).In the form of a stand-alone film, the composites of the presentinvention can be useful as an electronics-type substrate such as a basefilm for a flexible circuit laminate. The films of the present inventionmay also be stacked in a multi-layer printed circuit board asresist-type layer, or specifically a resistor layer. The films of thepresent invention may also be useful as a resist layer material in a“prepreg” material, sealing material for semiconductor package, a matrixfor fiber reinforced composite material, membranes, or moldingmaterials, or in similar type applications.

In one embodiment of the present invention, a metal layer is laminatedon one side (or both sides) of the blended polyimide/doped-polyanilinefilm. Commonly, the metal layer is in the form of a metal foil made ofcopper, nickel, titanium, or alloys of different metals.

In another process, the blend film of the present invention can be curedand then metallized with a sputtering an electroplating operation, (orlaminated to a metal foil) to form a composite blend film-metal layerlaminate. In such a process, the blend film of the present invention canbe first cured (i.e. the polyamic acid is cured to a polyimide) and theneither sputter coated with a seed coat of metal and then electroplated,or simply laminated to an existing metal foil. In a sputteringoperation, once a seed coat of metal is placed on either one side (or onboth sides of the blend composite film) a thicker coating of metal canthen be “plated-up” using an electroplating bath. Sputter and platingmetalization operations, as well as cast-on-metal operations and metalfoil lamination operations, are well known in the art and need not befully described herein.

In other embodiments of the present invention, thepolyimide/doped-polyaniline compositions are incorporated into liquids,pastes, films, or other laminate substrates and/or the like, to be usedfor screen printing, solution coating, spray coating or injectingmolding. The compositions of the present invention can be cast orco-extruded onto a film or printed circuit board, particularly filmscontaining at least one other electrically conductive layer, for use(ultimately) as an interior layer in a flexible circuit.

The substrates of the present invention can be incorporated intomultilayer laminates, and/or incorporated into an integrated circuitdevice, such as, a level one packaging substrate for an integratedcircuit. The substrates of the present invention can also be used inlevel 2 packaging as a substrate in a larger integrated circuitassembly. Optionally, the blend films of the present invention can bederived from a thermoplastic polyimide component and can be used to makea multilayer polyimide construction. In these film constructions, thethermoplastic electrically conductive blend film layer is used as theouter film layers of a three-layer laminate. A non-thermoplastic, highmodulus polyimide (e.g. a polyimide derived from BPDA, PMDA, 4,4′-ODA,and PPD monomers) can be used as the inner layer. In addition, the innerlayer polyimide may optionally be a blend of a polyimide component and adoped polyaniline component so that the inner layer is also electricallyconductive. In another embodiment of the present invention, both theouter layers and the inner layer are derived from a thermoplasticpolyimide component and a doped polyaniline component.

In one embodiment, a substrate in accordance with the present inventiondirectly or indirectly supports (or protects) an integrated circuit dieand further comprises a conductive pathway on a surface, andalternatively (or in addition), provides a conductive pathway within orthrough the substrate. In one embodiment, a substrate in accordance withthe present invention is used as a component of an IC packagingcomposition, such as, a chip on lead (“COL”) package, a chip on flex(“COF”) package, a lead on chip (“LOC”) package, optoelectronic package,flat-wire applications, a multi-chip module (“MCM”) package, a ball gridarray (“BGA” or “μ-BGA”) package, chip scale package (“CSP”) or a tapeautomated bonding (“TAB”) package. Alternatively, a substrate inaccordance with the present invention can be used as a component of awafer level integrated circuit packaging substrate comprising aconductive passageway having one or more of the following: a wire bond,a conductive metal, and a solder bump.

Substrates of the present invention can have a thickness in a rangebetween and including any two of the following: 5, 8,10, 15, 20, 25, 30,35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115,120, and 125 microns. In one embodiment, at least a portion of thesubstrate is laminated to a metal layer.

In one embodiment, a substrate in accordance with the present inventionis used as a component of an imaging transfer belt in a high-speed colorcopying machine. In other embodiments, a substrate in accordance withthe present invention can be used as a multilayer (flexible or rigid)circuit board or as a component of an anti-static material.

In another embodiment, a substrate in accordance with the presentinvention is used as a self-adherable film for use as an image transferbelt (in a color copying machine) or the like, where self-adhesion canbe induced by using heat, pressure or a combination thereof.

Substrates of the present invention can be incorporated into multilayerfilm structures, comprising an inner layer and two outer layers: i.wherein the outer layers are adjacent to the inner layer; ii. wherein atleast 50, 60, 70, 80, 85, 90, 95, 98 or 100 weight percent of the outerlayers are derived from a thermoplastic polyimide component and a dopedpolyaniline component; and iii. wherein at least 50, 60, 70, 80, 85, 90,95, 98 or 100 weight percent of the inner layer is derived from anon-thermoplastic polyimide. Alternatively, the multilayer film cancomprise an inner layer and two outer layers: i. wherein the outerlayers are adjacent to the inner layer; ii. wherein at least 50, 60, 70,80, 85, 90, 95, 98 or 100 weight percent of the outer layers are derivedfrom a thermoplastic polyimide component and a doped polyanilinecomponent; and iii. wherein at least 50, 60, 70, 80, 85, 90, 95, 98 or100 weight percent of the inner layer is derived from anon-thermoplastic polyimide component and a doped polyaniline component.

EXAMPLES

The following EXAMPLES were conducted on the pilot scale usingmanufacturing grade equipment. To disperse the polyaniline particles indimethylacetamide solvent, a Netzsch horizontal media mill, modelLMZ-25, was used with a kinetic dispersion machine.

A slurry of polyaniline powder and dimethylacetamide solvent was firstprepared using a 200-gallon kinetic dispersion, mixing machine. Thepowder was dumped into the solvent and dispersed for 45 minutes.

The subsequent media milling, through the LMZ-25 media mill, wasaccomplished by circulating the slurry from the kinetic dispersionmachine through the media mill using a diaphragm pump. The LMZ-25 millground the particles by using internal moving baffles to pass the slurryover the media. The batch make-up recipe for each of the differentEXAMPLES is listed below.

The particle size of the polyaniline slurries was measured using aHoriba LA-910 laser scattering particle size analyzer. The index ofrefraction was set to 1.24 for each measurement. The circulation pumpand agitation set points were set to a value of three. The analyzer wasfilled with 100 ml of dimethylacetamide and 0.5 ml of doped polyanilineslurry was added (to the original 100 ml of dimethylacetamide) for eachsample point.

Gloss factor measurements were made using a BYK Gardner Micro Tri-GlossMeter set at a measurement angle of 85 degrees. Samples were at every 8inches on a 40-inch wide strip. The five measurements were averaged andthe average was recorded as the gloss factor value for each sample.

Surface roughness was measured using a SurfCom 570A system utilizing aone-micron tip and a light-load contact diamond stylus. The instrumentmeasured the Ra roughness by taking two readings over a 24-millimeterdistance. The two values were averaged and the average was recorded asthe roughness Ra factor for each sample.

Surface resistivity measurements were taken using an Advantest R-8340AUltra High Resistivity Meter utilizing a HR Resistivity Test Fixture andBase Plate. The unit was set to measure at 1000 volts surface with the“electrical discharge function” turned ON to remove residual staticcharge. Measurements were taken after 30 seconds of exposure to allowequilibration of the system charge. Measurements were taken every 8inches across a 40-inch wide strip of film. The five measurements wereaveraged and the average was recorded as the surface resistivity foreach sample.

Examples 1-6

In the following example, 1455 lbs. of dimethylacetamide was charged toa 200 gallon kinetic dispersion milling machine. Next, 47 lbs. of 85percent aqueous phosphoric acid was added. Over 30 minutes, 98 pounds ofpolyaniline powder (in an Emeraldine salt form, “ES salt”) was added andthen additionally dispersed for 30 minutes.

After using kinetic dispersion, the slurry was tested to determine theaverage particle size of the slurry. The average particle size wasbetween 8 and 20 microns depending on the time in which the sample wasallowed to settle. 99.9% of the measured particles in the slurry was inthe range of 18 to 25 microns.

Next, the slurry was circulated through the Netzsch horizontal mediamill using diaphragm pump. The particle size coming from the dischargeof the media mill was monitored over the next 100 hours. FIG. 1 showsthe average particle size of the slurry over time.

The initial particle size of EXAMPLES 1-6 after 97 hours of millingthrough the media mill was 1.8 microns. The largest 99.9% of theparticles was 4.3 microns. After 24 hours, under normal agitation, theparticles had an average particle size of 2.0 microns. The largest 99.9%of the particles were 4.4 microns. Viscosity remained constant at about0.2 poise.

The slurries were transferred to an agitated storage tank through a25-micron filter. Periodic checking of the average particle size of theslurry showed no significant change (i.e. an increase in averageparticle size or gelling of the slurry) over a 24-hour period.

The slurries were blended with a solution of polyamic acid derived from50 mole % RODA, 10 mole % PMDA and 40 mole % ODPA. The initial viscosityof the polyamic acid was 85 poise and weight percent solids was 22%solids in DMAc.

After addition of the polyaniline slurry to the polyamic acid, theviscosity of each EXAMPLE was raised to 750 poise by adding additionalPMDA from a 6 weight percent solution. The final solution containinghigh viscosity polyamic acid and doped polyaniline was adequate forcasting.

The mixed polymers of EXAMPLES 1-6 were cast onto a flat surface using acoat-hanger-style casting die forming different films. The surface ofthe film on the flat surface is known as the belt-side, the oppositeside of the film is known as the air-side.

The films were heated from 40° C. to 150° C., over 45 minutes to producesemi-cured polyamic acid films. The semi-cured polyamic acid films werethen passed through a high temperature oven to cure the polyamic acid topolyimide. The high temperature oven exposed the films to airtemperatures between 575° C. and 650° C. for 20 minutes. The final filmswere greater than 99% polyimide containing dispersed therein, dopedpolyaniline particles at different volume loading levels where thepolyaniline had an average particle size of about 2.0 microns. Thefollowing films were formed under varying conditions and had thefollowing results.

Properties Example 1 Example 2 Example 3 Example 4 Polyaniline Loading(%) 10.5 12.5 12.0 10.5 Point Thickness 83.3 76.7 76.7 80.3 (microns)MD/TD Elongation (%) 115.1 97.0 95.5 86.6 MD/TD Tensile Strength 21.8820.34 20.31 19.24 (Kpsi) MD/TD Modulus (Kpsi) 401.94 377 429 466 Glossfactor 91.8 93.3 93.1 95.4 Surface Resistivity 3.43E12 9.94E11 1.06E122.16E12 (1000 V) 5 minutes after curing oven Surface Resistivity 2.61E111.07E11 1.64E11 2.55E11 (1000 V) 24 hours after curing oven Roughness(Ra) microns 0.09 0.12 0.11 0.07 Properties Example 5 Example 6Polyaniline Loading (%) 10.5 10.5 Point Thickness (mil) 80.5 80.5 MD/TDElongation (%) 84.5 86.4 MD/TD Tensile Strength 18.17 18.06 (Kpsi) MD/TDModulus (Kpsi) 348 354 Gloss Factor 96.3 95.4 Surface Resistivity (1000V) 1.74E12 3.25E12 5 minutes after curing oven Surface Resistivity (1000V) 1.05E11 2.46E11 24 hours after curing oven Roughness (Ra) microns0.09 0.10

Comparative Examples 1-2

In the following COMPARATIVE EXAMPLES, 805 lbs. of dimethylacetamide wascharged to a 200-gallon kinetic dispersion, milling machine. Next, 16.9lbs. of 85 percent aqueous phosphoric acid (dopant) was added. Over 30minutes, 52.5 pounds of polyaniline powder in the ES salt form was addedand then additionally dispersed for 30 minutes.

After milling, the slurry was tested to determine the average particlesize of the slurry. In these COMPARATIVE EXAMPLES, the average particlesize of the polyaniline slurry was between 8 to 10 microns depending onthe sample taken and the time in which the sample was allowed to settleprior to being analyzed. 99.9% of the measured particles in the slurrywere in the range of 18 to 25 microns.

Next, the slurry was circulated through the Netzsch horizontal mediamill using diaphragm pump. The particle size coming from the dischargeof the media mill was monitored over the next 20 hours until the averageparticle size of the slurry was about 7.5 microns and 99.9% of theparticles were smaller than 20 microns. The slurry was transferredwithout any filters.

The following slurry was mixed with polyamic acid, cast and cured in thesame manner as the EXAMPLES. The following film data was obtained.

Properties Comparative Ex. 1 Comparative Ex. 2 Polyaniline Loading (%)8.1 9.0 Point Thickness (microns) 85.9 80.2 MD/TD Elongation (%) 80.165.7 MD/TD Tensile Strength 17.9 16.55 (Kpsi) MD/TD Modulus (Kpsi) 368385 Gloss Factor 65.7 63.2 Surface Resistivity (1000 V) 2.49E13 1.82E135 minutes after curing oven Surface Resistivity (1000 V) 3.0E12 1.5E1224 minutes after curing oven Roughness (Ra) microns 0.18 0.19

The results of these two COMPARATIVE EXAMPLES illustrate that when theaverage particle size of the polyaniline filler is about 7.5 microns,the films produced have a lower gloss factor and higher roughness.

Comparative Example 3

The following COMPARATIVE EXAMPLE was using 358.8 (g) of DMAc, 13.38 of85% aqueous phosphoric acid, and 28.0 grams of polyaniline powder (ESsalt). The three components were milled in a high shearlaboratory-milling machine, for 300 minutes, drawing 1.8 kilowatts ofpower.

The viscosity of the slurry, at an average particle size of 1.8 microns,was about 1 poise. The slurry was milled down further to an averageparticles size of less than 0.5 microns. As the average particle size ofthe slurry decreased to about 0.01 microns, the viscosity of the slurrydramatically increased. The viscosity at this size range was measured tobe about 2,000 poise. A particle size analysis at this stage revealedthat the slurry contained only about 1 to 3 percent of the particles inthe 500 to 1000 micron size range. The physical character of the slurryresembled a gel, or gelatinous liquid.

A film was produced using the slurry above (the slurry originally havingan initial average particle size of about 0.01 microns). The viscosityof the slurry was so high some additional solvent was added to mix theslurry with polyamic acid to cast a film. A particle size analysis ofthe slurry at this stage showed that 99.9 percent of the particles inthis slurry were smaller than about 534.3 microns and the final dilutedviscosity was about 4,500 poise. COMPARATIVE EXAMPLE 3 produced apolyimide/polyaniline blend film having a Ra roughness number of about0.89 microns and a gloss factor of about 55.0.

1. An electrically conductive, polyimide based substrate comprising: a polymeric blend of at least a polyimide component and a polyaniline component, the polyaniline component being: a. present from 5 to 40 weight percent of the total substrate, and b. derived from a liquid dispersion of doped or un-doped polyaniline particles having an average particle size from 0.5 to less than 5 microns, to provide at least one substrate surface having: i. a surface electrical resistivity from 10,000 to 10¹⁴ ohms per square, ii. a surface gloss factor from 70 to 120, and iii. a surface roughness, Ra factor (microns), from 0.05 to 0.15.
 2. A substrate in accordance with claim 1, wherein the thickness of the substrate is from 5 to 125 microns.
 3. A substrate in accordance with claim 1, wherein the substrate is created in part by forming a doped polyaniline dispersion and subjecting the dispersion to a shearing force over a sufficient time to reduce the doped polyaniline particles to an average size from 4.9 to 0.5 microns and then mixing the doped polyaniline dispersion with a polyimide precursor solution.
 4. A substrate in accordance with claim 1, wherein at least a portion of the substrate is also laminated to a metal.
 5. A substrate in accordance with claim 1, wherein the polyimide component is derived from a polyamic acid precursor created at least in part by contacting one or more dianhydride components with one or more diamine components, the dianhydride component being selected from a group consisting of: pyromeiritic dianhydride, 4,4′-oxydiphthallc anhydride, bis(3,4-dicarboxyphenyl) sulfone dianhydride, 2,2-bis(3,4-dicarboxyphenyl) 1,1,1,3,3,3,-hexafluoropropane dianhydride (6FDA), 2,2′-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride and combinations thereof.
 6. A substrate in accordance with claim 1, wherein the polyimide component is derived from a polyamic acid precursor created at least in part by contacting one or more dianhydride components with one or more diamine components, the diamine component being selected from a group consisting of: 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 4,4′-diaminodiphenyl ether (4,4′-ODA), 3,4′-diaminodiphenyl ether (3,4′-ODA), 1,3-bis-(4-aminophenoxy) benzene (APB-134 or RODA), 1,3-bis-(3-aminophenoxy) benzene (APB-133), 2,2-bis -[4-(4-aminophenoxy)phenyl]propane (BAPP), bis-(4-(4-aminophenoxy)phenyl sulfone (BAPS), 4,4′-bis(3-aminophenoxy)diphenylsulfone (m-BAPS), 4,4′-bis-(aminophenoxy)biphenyl (BAPB), bis(4-[4-aminophenoxy]phenyl) ether (BAPE), ), 1,6-hexamethylenediamine (HMD), 2,2′-bis-(4-aminophenyl) 1,1,1,3,3-hexafluoro propane (6F diamine), and combinations thereof.
 7. A substrate in accordance with claim 1, wherein the polyaniline component is selected from the group consisting of Emeraldine base polyaniline, Emeraldine salt polyaniline, leucoEmeraldine polyaniline, nigraniline polyaniline, and pernigraniline polyaniline.
 8. A substrate in accordance with claim 1, wherein the polyanline component is derived from an aniline component selected from the group consisting of aniline, alkylaniline and alkoxyaniline.
 9. A substrate in accordance with claim 1, wherein the polyaniline component is dispersed in a polar solvent selected from a group consisting of: dimethylacetamide (DMAc), N-methylpyrrolidinone (NMP), gamma-butyrolactone, N,N′-dimethyl-formamide (DMF), dimethyl sulfoxide (DMSO), tetramethyl urea (TMU), N,N-dialkylcarboxylamides, N,N-diethylformamide, N,N-diethylacetamide, dimethylsulfoxide, N-cyclohexyl-2-pyrrolidone, dimethylsulfone, hexamethylphosphoramide, tetramethylenesulfone, diglyme, and pyridine.
 10. A substrate in accordance with claim 9, whereIn the polyaniline component is dispersed in a mixture of a first solvent and a second solvent, wherein the first solvent has a surface tension between 34 mN/m and 42 mN/m, and wherein the second solvent has a surface tension either between and including 20 and 33.5 mN/m or between and including 42 and 500 mN/m.
 11. A substrate in accordance with claim 9, wherein the polyaniline component is dispersed in a mixture of a first solvent and a second solvent wherein the second solvent is selected from the group consisting of water, alcohols, ethers, and ketones.
 12. A substrate in accordance with claim 1, wherein the polyaniline component is doped with a protic acid having an acid dissociation constant (pKa) equal to or less than 4.8.
 13. A substrate in accordance with claim 1, wherein the polyaniline component is doped with an acid selected from a group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hypophosphoric, phosphonic acids, hydrofluoroboric acid, hydrofluorophosphoric acid, hydrochloric acid, aliphatic acids, aromatic acids, alicyclic acids, and polybasic acids.
 14. A substrate in accordance with claim 1, said substrate comprising all or part of an imaging transfer belt in a high-speed color copying machine.
 15. A substrate in accordance with claim 1, said substrate being a component of a multilayer flexible or rigid circuit board.
 16. A substrate in accordance with claim 1, said substrate being a component of an anti-static blanket.
 17. A substrate in accordance with claim 1, said substrate being a component of a circuit package.
 18. A single layer substrate in accordance with claim 1, further comprising a filler.
 19. A single layer substrate in accordance with claim 1, further comprising a filler selected from the group consisting of metal, metal oxides, carbon fibers, graphite, and semi-conductor powders.
 20. A substrate in accordance with claim 1, wherein the substrate is a component of a packaging composition, the packaging composition being a chip on lead (“COL”) package, a chip on flex (“COF”) package, a lead on chip (“LOC”) package, a multi-chip module (“MCM”) package, optoelectronic package, flat-wire applications, a ball grid array (“BGA” or “μ-BGA”) package, chip scale package (“CSP”) or a tape automated bonding (“TAB”) package.
 21. A substrate in accordance with claim 1, wherein the substrate is a component of a integrated circuit packaging substrate comprising a conductive passageway, said passageway comprising one or more members of the following group: a wire bond, a conductive metal, and a solder bump.
 22. A substrate in accordance with claim 1, wherein the substrate is a self-adherable film using heat, pressure or a combination thereof.
 23. A substrate in accordance with claim 1, wherein the substrate is a seif-adherable film and wherein the film is used as an image transfer belt in a color copying machine. 